Hair loss is a problem which many men and women experience in their lifetime. The most common cause of hair loss is associated with the normal aging process. The process of losing one's hair is most often gradual. It is often first noticed during washing or grooming. This observation is imprecise in predicting permanent hair loss, as most individual hair follicles go into a dormant period (20% of the hair population at any one time) and a reduction of hair population may be partly the result of this process although this process is usually uniform.
The distinguishing factor which differentiates permanent hair loss from cyclical hair loss is that the population of the hair decreases gradually in affected areas resulting in a permanent loss of hair and a reduction of hair population and hair density. The permanent loss of hair is often selective by anatomical site. In men, hair loss follows one pattern ("Male Pattern Baldness" or "Androgenic Alopecia") and in women it follows another pattern. The process of losing hair also occurs at different rates, for different periods of time and at different ages, even in the same individual.
Dermatologists recognize many different types of hair loss, the most common by far being "androgenic alopecia" wherein human males begin losing scalp hair at the temples and on the crown of the head in early adult life. This type of hair loss is more common and more severe in males, hence its common name "male pattern baldness." However, similar patterned baldness occurs in women, though it progresses more slowly and does not reach the end stage of complete denudation. An effective treatment for these and related conditions has long been sought.
Many women think thinning hair is abnormal or unnatural, i.e., a man's problem. Some believe that if their hair is thinning, then they must be sick, or that it's stress related. Among women younger than 50 who experience hair thinning, most assume that it is caused by something external, while women over 50 normally attribute it to just another part of aging. Temporary conditions such as pregnancy, medication, diet, or stress can cause hair thinning. However, for 70% of the women who experience the condition, it can be attributed to androgenetic alopecia.
Both women and men experience androgenetic alopecia and approximately 50 million men have hereditary hair thinning compared to nearly 30 million women. However, it affects the genders differently. While men experience "pattern baldness", vertex balding and/or receding frontal hairline, women generally experience diffused thinning over the top of the head or crown, while most often maintaining a frontal hairline. Androgenetic alopecia is non-discriminating, affecting men and women of all races and ethnicities, and is passed down by one's parents.
Surprisingly, it is not something that happens to women only after menopause. It can begin as early as the 20s and is so common, that by age 35, almost 40% of women demonstrate some signs of hair thinning. By the age of 50, approximately 50% of women will experience some degree of hair thinning.
As one ages, a combination of heredity, the effects of hormones and age causes certain hair follicles to get smaller and smaller. This prevents the hair from fulfilling its regular growth process, which is usually 1/2 inch per month. With androgenetic alopecia, genetically predisposed follicles gradually become smaller and the period of time in which the hair grows is reduced--a process known as miniaturization. And hair that can only grow for a short time is shorter, thinner, even colorless.
There are two types of hair follicles which produce either "terminal hairs" or "vellus hairs." Terminal hairs are coarse, pigmented, long hairs in which the bulb of the follicle is situated deep in the skin, usually in the subcutaneous tissue. Vellus hairs, on the other hand, are fine, thin, non-pigmented short hairs whose bulbs are located superficially in the upper dermis. In patterned alopecia, follicles which produce terminal hairs are gradually converted to vellus ones through a miniaturization process.
Along with this progressive involution there inevitably occurs changes in the proportion of hairs in the various phases of the hair cycle. All follicles pass through a life cycle that includes three phases namely, (1) anagen (2) catagen and (3) telogen. The anagen phase is the period of active hair growth and on the scalp generally lasts from 3-6 years. Catagen is a short transitional phase when the follicle contracts in preparation for a resting period. It lasts a couple of weeks. In telogen, the follicle is in a resting phase where all growth ceases and the hair becomes consisted of short "club" hairs. When a new cycle begins, the club hair is shed. Telogen scalp hairs are relative short-lived, and last only about three to four months.
Normally, approximately 90% of scalp hairs are in the anagen phase, less than 1% exist in the catagen phase and the remainder are in the telogen phase. With the onset of patterned baldness, a successively greater proportion of hairs are in the telogen phase, with correspondingly fewer in the active growth anagen phase.
Additionally, there may be some actual loss of hair follicles but this is limited to the last final phase. For the most part, the visible diminution in the bulk of hair is due to the miniaturization of the follicles. In completely bald areas, all the follicles are in the vellus phase producing ugly, fine, short, non-pigmented hairs which are cosmetically useless. It may take 20 to 30 years for the distinctly anagen follicles on the crown to become transformed into a uniform population of vellus follicles.
Patterned baldness is sometimes called androgenic alopecia because male hormones are necessary for its development. It does not occur before adolescence, nor in castrates. Attempts to prevent alopecia by hormonal treatments by using anti-androgens or female hormones have failed. A hereditary component is also recognized since patterned alopecia runs in families. Despite intensive investigation, the mechanism whereby terminal follicles convert to vellus ones is unknown.
At the present time, one effective treatment for patterned alopecia is hair transplantation. Plugs of hair-bearing skin from the back of the scalp are transplanted into the bald areas. The procedure is costly and painful. Hundreds of plugs must be transplanted to create an appearance of hairiness and it is virtually impossible to obtain anything near the original density and thickness of terminal hair.
Many other approaches for creating or reversing patterned alopecia have been tried including ultra-violet radiation, massage, chemical irritation and innumerable natural products and herbs. However, none of these have been generally accepted as effective.
Pharmaceuticals offer a more rational approach although most tested have been found to be poorly metabolized and the results have been less than satisfactory. In Europe, a schedule of estrogens and anti-androgens have been administered orally to balding females with inconsistent results and with obvious limitations.
The topical application of minoxidil is currently the most effective therapy for patterned alopecia. Minoxidil is a well-known pharmaceutical agent marketed by the Upjohn Company (Kalamazoo, Mich.) and administered in tablet form for the treatment of hypertension. Numerous investigators have demonstrated that it can also stimulate visible hair growth in a majority of balding subjects. The structure and use of this compound is described in U.S. Pat. Nos. 4,139,619 an 4,596,812 to Chidsey et al. This compound has varying degrees of efficacy for moderating androgenic alopecia, depending on the degree of baldness, its duration, the age of the patient and, of course, on the concentration of the drug in an appropriate vehicle.
The ability to diagnose hair loss in its earliest stages is difficult and compounded by many aesthetic factors which reflect the visual contrast between hair color and character against the color background of the scalp. In individuals with black course hair and white skin, the contrast is dramatic and hair loss is evident early in the process. In individuals with blond hair and blond skin, significant hair loss can occur before it is evident as the contrast between scalp and hair color is minimal.
In all cases, the diagnosis of hair loss is a subjective assessment made by either doctor or patient, and the response to treatment is often subjective as well. Heretofore, objective measurements of hair density has not been practical and as a result the effectiveness of snake oils of many varieties as well as medicines approved by the Federal Drug Administration go unproven for any selected individual.
It is an object of the present invention to provide a method and means for measuring the degree and rate of hair loss in a given individual, and in particular, in women. The device and method not only is useful in determining how much hair is lost, but, when used in conjunction with the therapies discussed above, how much hair may be regained through the stimulation of new growth and/or the rate at which such hair loss may be delayed and/or retarded.